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659  structures 1705  species 20  interactions 12929  sequences 720  architectures

Clan: Trefoil (CL0066)


Beta-trefoil superfamily Add an annotation

This family corresponds to a large set of related beta-trefoil proteins [1]. The beta-trefoil is formed by six two-stranded hairpins [2]. Three of these form a barrel structure and the other three are in a triangular array that caps the barrel. The arrangement of the secondary structures gives the molecules a pseudo 3-fold axis.

This clan contains 15 families and the total number of domains in the clan is 12929. The clan was built by A Bateman.

Literature references

  1. Ponting CP, Russell RB; , J Mol Biol 2000;302:1041-1047.: Identification of distant homologues of fibroblast growth factors suggests a common ancestor for all beta-trefoil proteins. PUBMED:11183773 EPMC:11183773
  2. Murzin AG, Lesk AM, Chothia C; , J Mol Biol 1992;223:531-543.: beta-Trefoil fold. Patterns of structure and sequence in the Kunitz inhibitors interleukins-1 beta and 1 alpha and fibroblast growth factors. PUBMED:1738162 EPMC:1738162


This clan contains the following 15 member families:

AbfB Agglutinin Botulinum_HA-17 CDtoxinA DUF569 Fascin FGF FRG1 IL1 Ins145_P3_rec Kunitz_legume MIR Ricin_B_lectin RicinB_lectin_2 Toxin_R_bind_C

External database links

Domain organisation

Below is a listing of the unique domain organisations or architectures from this clan. More...

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The table below shows the number of occurrences of each domain throughout the sequence database. More...

Pfam family Num. domains Alignment
Ricin_B_lectin (PF00652) 3906 (30.2%) View
FGF (PF00167) 1638 (12.7%) View
MIR (PF02815) 1582 (12.2%) View
RicinB_lectin_2 (PF14200) 1501 (11.6%) View
Fascin (PF06268) 817 (6.3%) View
Kunitz_legume (PF00197) 766 (5.9%) View
Ins145_P3_rec (PF08709) 714 (5.5%) View
IL1 (PF00340) 589 (4.6%) View
CDtoxinA (PF03498) 430 (3.3%) View
AbfB (PF05270) 334 (2.6%) View
FRG1 (PF06229) 253 (2.0%) View
DUF569 (PF04601) 184 (1.4%) View
Toxin_R_bind_C (PF07951) 143 (1.1%) View
Agglutinin (PF07468) 39 (0.3%) View
Botulinum_HA-17 (PF05588) 33 (0.3%) View
Total: 15 Total: 12929 Clan alignment

Please note: Clan alignments can be very large and can cause problems for some browsers. Read the note above before viewing.

Family relationships

This diagram shows the relationships between members of this clan. More...

Species distribution

Tree controls


This tree shows the occurrence of the domains in this clan across different species. More...



There are 20 interactions for this clan. More...

Interacting families
Ricin_B_lectin RIP
Toxin_R_bind_C Toxin_trans
Agglutinin Agglutinin
IL1 ig
CDtoxinA Exo_endo_phos
AbfB ArabFuran-catal
FGF ig
Fascin Fascin
Kunitz_legume Thioredoxin


For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the MSD group, to allow us to map Pfam domains onto UniProt three-dimensional structures. The table below shows the mapping between the Pfam families in this clan, the corresponding UniProt entries, and the region of the three-dimensional structures that are available for that sequence.

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